“I once sat on a jury in a minor criminal trial. The trial itself was unremarkable, but I’ll never forget two elements of the judge’s instructions to the jury. The first was his point that ‘reasonabledoubt’ means what it says: It isn’t enough for a juror to assert a vague doubt or a hunch; there has to be a reason for it. The second was his advice about how to weigh conflicting testimony: There are no special criteria that apply only in court. To decide who is lying and who is telling the truth, the juror uses the same human radar that he or she has developed to navigate everyday life.